go-template-http

README

go-template-http

go-template-http is a simple HTTP server written in Go for rendering Go templates.

It does one thing and does it well.

getenv

It supports rendering environment variables through a custom getenv function.

For example, the following Go template shows the $PATH variable:

$ curl -d '$PATH is: {{getenv "PATH"}}' localhost:8080
$PATH is: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

environ

To get an overview of all available environment variables, the custom environ function can be used:

$ curl -d '{{range environ}}{{println .}}{{end}}' localhost:8080
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=cf70703ecf6d
HOME=/

Motivation

The motivation for creating this tool was to have a way to share build secrets with docker build without embedding the secret into the image.

It's a kindof tricky thing to do, but it's possible by calling the network, for example:

$ export BITBUCKET_USERNAME=...
$ export BITBUCKET_PASSWORD=...
$ docker network create build
$ docker run --env=BITBUCKET_USERNAME --env=BITBUCKET_PASSWORD --network=build --name=secrets --rm -d aude/go-template-http
$ cat << '_EOF_' > Dockerfile
FROM python

WORKDIR /app

RUN printf '%s\n' \
	'machine bitbucket.org' \
	'login {{getenv "BITBUCKET_USERNAME"}}' \
	'password {{getenv "BITBUCKET_PASSWORD"}}' \
	| curl --fail --data-binary @- http://secrets:8080/ > ~/.netrc \
	&& pip install git+https://bitbucket.org/your-company/private-package.git \
	&& rm ~/.netrc

# extra check, to prove that ~/.netrc is not embedded in Docker image
RUN test ! -f ~/.netrc

COPY . .

CMD ["python", "main.py"]
_EOF_
$ docker build --network=build .
...
$ docker stop secrets
$ docker network rm build